In Taiwan, the clan associations have some leverage over local affairs, including elections of legislator, county mayor, county congressman, township heads, town heads and town councilman, and so on. Some critics observe that the clan associations have far more significant influence than political party in some counties such as Tao-yuan, Hsin-chu, etc. This thesis aims to explore the interaction between local faction and clan association in Taiwan through analysis on several cases about Tao-yuan county. The author will focus on the social network and bring forward the following assumptions: (1) politicians influence the result of an election by involving themselves in local faction; (2) politicians influence the result of an election by involving themselves in clan association; (3) local faction forms an alliance with clan association to influence the result of an election. In sum, the interactive patterns between local faction and clan association can be divided into four categories: (1) clan faction, i.e. local faction comprised primarily of members of clan association; (2) clan faction with some other clan ; (3) non-clan faction, i.e. local faction comprised primarily not of members of clan association; (4) local faction unrelated to any clan association. The author attempts to explain the following aspects: first of all, how local faction develops cooperation relationship with clan association in various elections in Tao-yuan county; secondly, the alliance between local faction and clan association will be a short-term or long-term relationship; furthermore, if clan association will be in the cooperative process dwindled into factious clubs. Finally, what kind of interest exchanges will exist between local faction and clan association? The major findings of this study were as the following: (1) local faction develops a long-term cooperation relationship with clan association in various elections in order to win; (2) local factions win over clan associations by providing service and fellowship; (3) clan association has tendency to dwindle into factious clubs.